First step towards a model system of the drug delivery network based on amide-POSS nanocarriers

Among the varied and diverse family of drug delivery systems (DDSs), such as polymer–drug conjugates, polymeric micelles, dendrimers and molecular containers, polyhedral oligomeric silsesquioxanes (POSS) occupy a special position within the group of biocompatible drug carriers. The extraordinary recommendation of POSS for such systems derives from their three-dimensional structure, nanoscale size, low toxicity, and efficient cellular uptake. These conjugates can be strictly designed compared for instance to micelles, dendrimeric-drug or polymer/inorganic hybrid composites, in which the amount of therapeutics attached to the carrier is rather random, and there is a high probability that some of the drug molecules can be completely trapped inside the ramified structures. The combination of fully functionalized amide-POSS and pharmaceuticals might create a so-called sophisticated DDS. In such a system, the adsorbed drug molecules can be released under physiological conditions and then the POSS-based carrier will be hydrolyzed (at pH 1⁄4 7.40) to a non-toxic carboxylic acid salt and a water soluble polyhedral oligomeric silsesquioxane containing an aminopropyl group that can be safely removed from the organism.